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PEP 627: Remove REQUESTED from the spec #1575

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Aug 26, 2020
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PEP 627: Remove REQUESTED from the spec #1575

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1bd3c50
Fix typo
encukou Aug 25, 2020
412a28e
Remove REQUESTED from the spec
encukou Aug 25, 2020
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31 changes: 16 additions & 15 deletions pep-0627.rst
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Expand Up @@ -136,7 +136,7 @@ except for ``*.pyc`` and ``RECORD`` itself.
(Note that PEP 376 is unclear on what was optional; when taken literally,
its text and examples contradict. Despite that, “both fields are optional“ is a
reasonable interpretation of PEP 376.
The alternative would be to mandate—rather rhan recommend—which files can be
The alternative would be to mandate—rather than recommend—which files can be
recorded without hash and size, and to update that list over time as new use
cases come up.)

Expand Down Expand Up @@ -204,21 +204,21 @@ any ASCII string in ``INSTALLER``, rather than a lowercase identifier.
It also suggests using the command-line command, if available.


The ``REQUESTED`` File
----------------------
The ``REQUESTED`` File: Removed from Spec
-----------------------------------------

The ``REQUESTED`` file is kept in the specification, with only tool-specific
notes removed.
The ``REQUESTED`` file is now considered a tool-specific extension.

It is made clear that while ``REQUESTED`` is optional, tools must handle it:
it can only be omitted only if it is known that a user did not request
installation directly.
Per :pep:`376`, ``REQUESTED`` was to be written when a project was installed
by direct user request, as opposed to automatically to satisfy dependencies
of another project. Projects without this marker file could be uninstalled
when no longer needed.

Note that tools that do not create this file effectively mark all installed
projects as “removable unless needed by another project”.
This was was the case with ``pip`` before version 20.2.
Before ``REQUESTED`` becomes commonplace, automatically uninstalling “orphaned”
projects should be done with care.
Despite the standard, many existing installers (including older versions of
``pip``) never write this file. There is no distinction between projects
that are “OK to remove when no longer needed” and ones simply installed by
a tool that ignores ``REQUESTED``. So, the file is currently not usable for its
intended purpose (unless a tool can use additional, non-standard information).


Clarifications
Expand All @@ -236,8 +236,9 @@ future PEPs:

* Encoding of the ``RECORD`` file
* Limiting or namespacing files that can appear in ``.dist-info``
* Marking the difference between projects installed by a tool that does not
support the ``REQUESTED`` file and projects installed as dependencies
* Marking the difference between projects installed directly by user request
versus those installed to satisfy dependencies, so that the latter can be
removed when no longer needed.


Copyright
Expand Down